1. Field of the Invention
The present invention relates to improvements in the construction of a bearing incorporated in a cone crusher and the like to crush stones or ores.
2. Prior Art
According to the known structure of a cone crusher, a sleeve is either solidly provided at the center of a frame or is integrally fitted with the frame by a method such as shrinkage fitting, bolting or the like, and an eccentric is idly inserted in the sleeve to be rotated while transmitted a rotating force from a drive unit, thereby gyrating a crushing head which is eccentrically inserted inside of the eccentric. Thus, the ores or stones carried therein are crushed by the gyration in the area between a lower liner mounted on the top of the crushing head forming a cone shape and an upper liner mounted on the frame facing the lower liner. The size (grading) of the crushed ores (products) depends upon the discharge opening referred to as the C.S.S. (closed side setting), and therefore when the setting becomes larger as a result of wear of both liners, it is necessary to compensate for the wear of the two liners to maintain the specified grading. Furthermore, when the crusher is stopped because of biting such material as tramp irons which are impossible to be crushed, it is necessary to temporalily enlarge the setting for the tramp iron release.
In view of the foregoing necessity, the conventional cone crusher has an adjustment ring with a thread for the wear compensation and springs for the tramp iron release, but has no set-indication system, and therefore the wear compensation must be performed by the following procedure, i.e., loosening the adjustment ring, turning it, checking the state of the discharge opening to be suitable and fixing the adjustment ring.
In order to improve such a conventional method, a cone crusher including a hydraulic mechanism has been proposed so that the eccentric with which the crushing head is internally engaged may be moved up and down while a torque is applied, as is disclosed in Japanese Patent Publication (examined) No. 57-58216 (FIG. 4) or in Japanese Utility Model Publication (unexamined) No. 58-178345 (FIG. 3).
Even in case of such improved cone crushers, however, due to the nature of the mechanism thereof, it is unavoidable that a fluctuating load is applied together with impact and torsion, in a direction orthogonal to the inclined surface of the lower liner, to the effective crushing area where the discharge opening between the lower liner 15' and the upper liner 16' is minimized, and accordingly the bearing member of the rotating portion to which the considerable moment is directly applied cannot be free from severe conditions. In other words, in the case of a hydraulic cone crusher as shown in FIG. 3, it is known to mount a spherical bearing on the main shaft in order to support the crushing head, and as a result of such a structure, an impulsive dynamic load and the weight of the crushing head are concentrated onto the bearing member, which is forced to wear considerably.
In order to protect the bearing member from such severe impulsive load, a further improvement has been proposed, in which in place of mounting the spherical bearing on the main body 9' of the crushing head, the eccentric 2' is supported through an upper outer bushing 50' and a lower inner bushing 51' provided on the upper and lower parts of the frame respectively. A lower thrust wearing plate 53' is provided on the upper part of the pistons, and an upper thrust wearing plate 52' is fixedly provided, in the shape of a concave ring, between the top end of the eccentric 2' which supports the main shaft 10' of the crushing head and the bottom of the main body 9' thereof. According to this proposal, the durability of the bearing system of the crusher is further improved.
In the case of such a structure as shown in FIG. 4, however, the weight of the whole gyrating member composed of a main body 9', a main shaft 10', a lower liner 15', etc., and the fluctuating impact load when crushing the feed materials by gyration are supported by the upper thrust wearing plate 52'. Since the upper thrust wearing plate 52' is fixedly provided on the top of the eccentric 2', it rotates at high speed together with the eccentric 2' to which the driving force is transmitted. Since the upper thrust wearing plate 52' rotates at high speed while supporting the considerable weight as a thrust bearing, problems such as easily breaking or exhausting the oil film is still unavoidable, resulting in seizure of the thrust bearing thereby. The situation is quite the same for the lower thrust wearing plate.